So pretty frequently it seems the groin muscle on my plant leg is pretty darn sore after playing. It's not noticeably sore during the round and I can't remember specifically injuring it at any point either.

I'm basically going to equate this to poor form on my part, so without the means to properly record myself can anyone out there possibly give me an idea or two that can fix my technique and alleviate the pain?

Are you flat footed in the pivot? That creates havoc. Is your final step super long like a spagat? That limits how much the hip to upper thigh joint can move and if you try to exceed the limit of flexibility, it can easily do harm. Multiply that with a long step and ouch! Would RICE rest, ice, compression and elevation help?

Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.

If you are old then the unknown cause is....getting old. Seriously, one of the attributes of age is never knowing the next body part which will hurt or why. It does not necessarily take a traumatic event to create an injury. I tore or strained a tendon in my ankle a couple months back doing apparently nothing. Half way through a round my ankle started hurting. I ignored it. It got worse. Within an hour I couldn't walk on it. It got better on its own. A few days later I played a tournament on it.

If you are not old then you have a spot somewhat weaker or more susceptible to injury. Actually we all do even if we don't know it yet (even a strong chain has a weakest link). So pay attention to it and stretch it out before and after rounds. It is possible there is one particular movement that is causing the problem. Generally the smoother and more flowing and balanced your form the less strain it puts on your body. Since smooth and balanced is a good way to throw anyway concentrating on that may help your game even if it doesn't help your groin.

There may be others who have actual medical knowledge (Hah! Why would we consult an expert when we have our buddies willing to give free advice??) who could suggest strengthening exercises or other effective resolutions (yoga? drugs? meditation? herbs? acupuncture? voodoo?).